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Monday, 16 July 2012

why China develops J-16 Fighter-bomber?

Recently a picture of China’s new fighter-bomber appeared on the network, it could be the legendary PLA Air Force J-16 fighter-bomber.

I believe that it is one kind of fighter-bomber aircraft, mainly because its front landing gear uses a dual-wheel and two-seat Su-27UBK and J-11BS’s use single wheel. Two-wheel shows the aircraft weight increase and at the same time requires the ability to landing on the poor conditions of airports, these are the typical fighter-bomber features.

Before the 3rd generation fighters, two-seater fighter-trainer aircraft only exist as a pilot’s training. After the 3rd generation fighter birth, this situation can not be maintained. The 3rd generations of aircraft usually have more advanced technologies, such as high-thrust turbofan engine, advanced avionics, fly-by-wire and composite materials are expensive, but if you only used to perform simple flight training mission, is obviously a waste. Besides, fighter-trainer aircraft itself also has a good tactical and technical performance, you can also perform many combat missions, in particular, is that it increases a crew member, you can share navigation, weapon control functions to reduce the burden on the pilot and the fighter is more suitable to perform some long-range combat missions: such as long-range patrols, ground attack and so on.

Israeli Air Force F-15D fighter not only early bear the combat mission, which is improved to be mounted electro-optical targeting cabin, dropping precision-guided bombs, but also have the ability to attack missile to launch the AGM-142 zone has become a multi-purpose combat aircraft, the European RAFLE and the EF-2000 two-seater designed from the beginning as a multi-role fighter to use the late Russian Su-27UBK fighter facelift the NO01P radar added attack mode, with the ability to launch precision-guided weapons, the Chinese Air Force conducted a comprehensive modification work on the Su-27UBK converted aircraft, either mount the R-77E active radar guided air-to-air missile to perform air superiority missions, you can also hang Upload ground missiles and precision-guided bombs for ground attack mission, has a multi-purpose combat aircraft.

Due to the few number of Su-27UBK in and Chinese Air Force and the lack of advanced training aircraft, PLA Air force has to training pilots with high intensity of Su-27UBK flying, resulting in rapid consumption of the life of these aircraft. In this case, China developed J-11BS two-seater fighter-trainer aircraft, J-11BS equipped with Chinese-made turbofan -10 engine, the nose is equipped with large-diameter pulse Doppler fire control radar, the avionics is joint avionics system based on 1553B data, with better scalability and upgrades of system. J-11BS has a glass cockpit to realize enhanced combat and attack performance with C4ISR datalinks supports.

Especially the construction of the Chinese Beidou navigation and positioning system has achieved a coverage of China and the surrounding areas, so that the Chinese Air Force can easily upgrade the existing conventional bombs to JDAM GPS-guided bombs, so that J-11BS has more methods to carry the day and night all-weather ground attack missions. Meanwhile, the Chinese airborne radar with synthetic aperture ground attack mode can detect ground targets, then target location information can be quickly acquired by Airborne Inertial Navigation System to input to the airborne satellite-guided bombs. PLA can make J-11BS with day and night all-weather precision strike capability.

However, this does not means that J-11BS fighter-bomber has equal or close to operational capability to Su-30MKK. J-11BS’s overall layout is same with the Su-27 series, so its body structure, pylons layout should be the same with the latter. According to the Su-27 specifications, it has 10 pylons, the largest weapong loading capacity could reach 6 tons, less than F-15E’s 11 tons, and Su-30MKK’s 10 tons.

J-11BS has 10 hardpoints, but four pylons on wing-tip and outer wing are light-load pylons to carry short-range air-to-air missiles, where heavier ground attack weapons can not be mounted. So J-11BS actually only has six heavy-load hardpoints. J-11BS inherites the advantages of the Su-27 series larger fuel load space, the machine can carry a maximum of oil over 8 tons. But the J-11BS still has its own limitations, first of all J-11BS four pylons under the fuselage, two of them located in the belly center extension and two below the inlet. J-11BS is a belly air intake layout, so that two of the center of the belly is located in the crevice of the two belly inlet, so that the weapon’s length, diameter wingspan are subject to greater restrictions.

J-11BS belly intake also limits the two fuselage pylons, the two pylons in the inlet below rarely mount weapons more than 1000kg. But modern long-range air-ground striking weapons in order to ensure a range and firepower, rarely lower than this weight number. Therefore, the two pylons is actually unable to mount a large air-surface weapons. Another limit is space. Especially precision-guided weapons, such as laser-guided bombs generally have a large control surface. If these weapons loaded on two fuselage pylons, thet arevery easy to hit the ground. Obviously the practical application of the two pylons is subject to considerable restrictions.

Therefore, we can see that J-11BS has 6 heavy hardpoints, but it actually only has three when loading 1000kg level guided weapons. J-11BS, after all, is to perform air superiority as the main task. Its relatively low wing loading can guarantee the performance of the aircraft’s air combat. But in the low-altitude penetration, lower wing loading may be subject to the interference of low-level airflow, resulting in jitter and bumps of the aircraft so that the aircraft is not easy at low altitude long penetration mission. So a complex control system is needed to install to suppress the interference of low-altitude air current.

So that we can know that major improvements of J-11BS is to increase the pylons to improve the weapon loading ability. I believe that the J-16 like to add a heavy hardpoint at the wing root, in order to improve the ability of weapon carrying.

Then the aircraft related structures of fuselage and wing should be strengthened, so the aircraft empty weight, maximum takeoff weight will increase, coupled with on the aircraft need to be in conditions of landing on imperfect airports, the high-pressure single-wheel front landing gear to be replaced low-pressure dual-wheel.

Despite the pylon increase brings larger weapon plug-in capacity of the aircraft, but it also increases the resistance of the aircraft, especially when mounted the large air-surface weapons is more serious. In addition, the weight increasing causes the decrease of aircraft fuel load factor, the aircraft’s range, endurance and combat radius will be reduced. So J-16 need to added the aerial refueling system.

Some may ask, China has developed the J-20 stealth combat aircraft, why development of the 3rd generation J-16 fighter-bomber? It is believed that this relates to the inherent limitations of the stealth aircraft, such as the ground attack capability. Stealth aircraft in order to ensure the stealth performance, airborne weapons with built its bomb bay, so it is difficult to mount a 1000 kg above ground precision guided weapons. Third generation of fighter-bombers, such as Su-30MKK and F-15E, can mount the heavy air-ground missiles to perform more extensive combat and air support missions.

Therefore, for the Chinese Air Force, the future composition of J-20 and J-16 jointly air-strike mode, can effectively raising the air strike capability of Chinese Air Force.